Rotary pump



Oct. 16, 1934. O.-S!EMEN EAL 1,976,896

ROTARY PUMP Filed May 3, 1933 1% vzniors Patented Oct. 16, 1934 ROTARYPUlVlP Otto Siemen and Johannes Hinsch, Itzehoe, Germany Application May3, 1933, Serial No. 669,082

ermany January 7, 1933 3 Claims. (Cl. 103-96) liquid annul s containedin a casing having a concentric or eccentric annular circulating channelwhich opens directly into the cells between the vanes and communicatesthrough the cells at one end with a suction port and at the other endwith a pressure port both disposed radially inward of the channel, thecasing being either stationary or rotatable or formed with a. rotatablesection.

The object of the invention is to reduce or eliminate the back pressurewhich generally occurs at the ports, and the invention consists broadlyin restricting the area of communication with the rotor cells of thoseparts of the circulation channel which communicate through the cellsdirectly with the ports.

Fig. 1 of the accompanying drawing shows by way of comparison an insideview of a pump of known construction,

Fig. 2 is an axial section of the same,

Fig. 3 is an inside view of a pump construction according to theinvention,

Fig. 4 is a cross-section of the latter,

Fig. 5 is an inside view of a modified form of the pump casing,

Fig.- 6 is a sectional view showing by way of comparison another knownchannel construction,

Fig. 7 shows the same channel modified according to the invention, and

Fig. 8 is a sectional view showing a further arrangement according tothe invention.

In Figs. 1 and 2, which show diagrammatically a pump of known typ e, thecasing is stationary and has an annular circulation channel arranged atone side of the rotor b.

In the circulation channel a, of which there may be one at each side ofthe rotor, an increasing rise in the pressure takes place which istransmitted to'the fluid in the rotor cells. This rise in the pressureis not desirable except in the median portion of the channel, i. e.,that portion of the channelwhich is not in direct communication with thesuction port 0 and the pressure port 61, since a rise in pressureoccurring at the ends of the channel brings about loss of power. This isdue to the fact that the centrifugal pressure in the rotor cells whichare in direct communication with the channel, is smaller than the risein pressure occurring at the leading end of the channel under a largehead. This causes a back current of the fluid from the channel a throughthe rotor cells to the suction port 0, i. e., a local dead circulationtakes place, as shown by the arrows at, which brings about a uselessconsumption of power.

When the head is large a similar action takes place at the end of thechannel where the rotor cells are in direct communication with thepressure port 11. Here the pressure in the port is determined by thehighest pressure inthe extreme end of the'irculation channel, where thepressure is higher than it is in the median portion of the channel, andthus, here also, a local dead circulation takes place, as shown by thearrows 1/.

These losses may be eliminated by shaping the channel so that the risein pressure is mainly relegated to the median portion of the circulationchannel.

Since the rise in pressure depends to a great extent on the size of thearea of direct communication between the rotor cells and thecircumferential or lateral circulation channel, it is possible, byreducing this area at the ends of the channel, to reduce or eliminatethe rise of pressure at these points. Since the flow of liquid from therotor cells into the channel can only take place in that half of thechannel which is farthest away from the centre of the rotor, and thereturn flow, only in that half thereof nearest the centre, as shown byarrows z in Fig. 2, the area of communication between rotor cells andchannel can be narrowed down to half the width of the channel, as shownin Figs. 3 and 4. Where the channel is very wide, the narrowing can evenbe carried beyond one half of the normal dimension thereof. By thisnarrowing of the channel the local circulation of liquid between rotorcells and channel on which the rise in pressure depends, will beprevented.

In the arrangement shown in Figs. 3 and 4, the narrowing of the area ofcommunication between rotor cells and channel is efiected by means of anoverhanging ledge 9. Fig. 5 shows a modified arrangement wherein thecorresponding channel portions 1 are narrowed in radial direction toachieve the object of the invention and widened in axial direction tomaintain the necessary cross-sectional area of the channel.

Fig. 6 shows another known arrangement wherein the circulation channelis partly lateral and partly circumferential and wherein detrimentalrise in pressure takes place at the ends of the channel as previouslyexplained. Fig. 7 shows the end portions of the channel modifiedaccording to the invention for preventing such rise in pressure.

When the channel is entirely circumferential,

the area of communication between the rotor cells and the ends of thechannel may be narrowed down as shown in Fig. 8 in order to. prevent'detrimental rise in pressures In all the constructions the modificationoi the channel ends will also bring about a considerable reduction infrictional losses.

We claim:

1. A rotary pump of the character described comprising a vaned rotor, acasing enclosing said rotor and forming the spaces between the. vanesinto closed cells, said casing having suction and pressure ports and anannular circulation channel all of which open direct into the rotorcells, said ports being disposed radially inward of the circulationchannel, the area of communication between the cells and the channel inthose portions of the latter which communicate with the same cells asthe ports being restricted to substantially half the normal channelareafor reducing local circulation of liquid.

2. A structure as claimed in claim 1 wherein the restriction of the areaof communication at the suction port is confined to the inner half ofthe channel area and that at the pressure port to the outer half of thearea relative to the centre of the rotor.

3. A structure as claimed in claim 1 wherein the channel is narrowed inradial direction to effect the restriction in the area of communicationand widened in axial direction to maintain the necessary cross-sectionalarea of the channel.

OTIO SIEMEN. JOHANNES HINSCH.

